There has recently been used a honeycomb structure body as a catalyst carrier using a catalyst function of an internal combustion engine, a boiler, a chemical reactor, a reformer for a fuel battery, etc., or as a filter, or the like, for trapping particulate in exhaust gas, in particular, diesel particulate.
A honeycomb structure body used for such a purpose had a problem of generating cracks or the like in the structure body because of an uneven thermal distribution in the honeycomb structure due to a sudden temperature change of exhaust gas or local heating. In particular, in the case of being used as a filter for trapping particle-like substances in exhaust gas from a diesel engine (hereinbelow referred to as DPF), it was necessary to regenerate the filter by removing deposited carbon particles such as soot by combustion. Since a localized heating at high temperature was inevitable at this time, high thermal stress was liable to be generated, and cracks were easily formed.
Therefore, there was proposed a method for bonding segments, into which a honeycomb structure body was divided, with a bonding agent. However, in such a honeycomb structure, bonding force between the honeycomb segment and a bonding layer is not sufficient still now, and there was a case of having an adhesion defect such as exfoliation from the interface between them. To solve such a problem, there has been proposed to arrange an under layer or an intermediate layer between the honeycomb segment and the bonding layer in order to improve bonding force and relax stress at the interface (see Patent Document 1 and Patent Document 2).
Patent Document 1: JP-A-2003-159908
Patent Document 2: JP-A-2003-848072